A DNA profile of the killer of a British tourist in Thailand is to be compared with databases worldwide, police said last night.

Backpacker Kirsty Jones, 23, of Brecon, was strangled while staying at a guest house in Chiang Mai, northern Thailand, three years ago on Sunday.

Initially, the owner of the guesthouse, a resident of Northern Ireland who discovered Miss Jones's body, was accused of her murder but all charges were later dropped.

Now Dyfed Powys Police say a DNA profile of the killer obtained from re-examination of exhibits from the scene is to be compared to those on police databases in 25 countries in an attempt to find a match.

Detectives recently travelled to Thailand and continue to help Royal Thai Police in their hunt.

They have also been asked to interview UK-based witnesses who may be able to provide information leading to the identity of the killer.

Detective Inspector Steve Hughson said, "We have a piece of Kirsty's killer in the DNA profile and we must ensure that the momentum of this inquiry is maintained within Thailand and that every effort is made to identify her killer and help her parents to understand why this tragedy happened."

Last year, on the second anniversary of the killing, Thai police said they were close to catching the murderer.

But they added that they needed more evidence to nail the person they suspected.

Police General Amnuay Pethsiri took charge of the case in February last year after the emergence of new evidence, including DNA samples from the crime scene provided by British police.

The case had earlier stalled after previous DNA tests on 14 suspects failed to match evidence from the scene. The new samples also failed to match, and reports arose in the Thai media of evidence tampering by suspects.